[PATCH] Cygwin: console: Ignore 0x00 on write().

Corinna Vinschen corinna-cygwin@cygwin.com
Fri Feb 21 11:05:00 GMT 2020


On Feb 21 10:43, Thomas Wolff wrote:
> On 21.02.2020 10:32, Corinna Vinschen wrote:
> > On Feb 20 17:38, Corinna Vinschen wrote:
> > > On Feb 20 17:22, Thomas Wolff wrote:
> > > > On 20.02.2020 17:04, Corinna Vinschen wrote:
> > > > > On Feb 20 23:49, Takashi Yano wrote:
> > > > > > On Thu, 20 Feb 2020 15:22:45 +0100
> > > > > > Corinna Vinschen wrote:
> > > > > > > On Feb 20 23:13, Takashi Yano wrote:
> > > > > > > > On Thu, 20 Feb 2020 14:44:59 +0100
> > > > > > > > Corinna Vinschen wrote:
> > > > > > > > > But, here's a question: Why do we move the cursor to the right at all?
> > > > > > > > > I assume this is compatible with legacy mode, right?
> > > > > > > > Hmm. This may be a bug of legacy console.
> > > > > > > > https://en.wikipedia.org/wiki/Null_character
> > > > > > > > says
> > > > > > > > (some terminals, however, incorrectly display it as space)
> > > > > > > > 
> > > > > > > > What about ignoring NUL in legacy mode too?
> > > > > > > I'd like that, but this may be a problem in terms of backward
> > > > > > > compatibility.  The behaviour is so old, it actually precedes even the
> > > > > > > import of Cygwin code into the original CVS repository, 20 years ago...
> > > > > > If so, can't we say it is the *specification* of TERM=cygwin
> > > > > > that NUL moves the cursor right?
> > > > > Good point.  Yes, in that case it's "working as designed" and
> > > > > we just leave it as is.  I push my patch.
> > > > See `man 5 terminfo`: if NUL does anything else than just padding, the
> > > > terminfo entry must contain a pad or npc entry, which it doesn't.
> > > > Trouble to be expected. I'd rather suggest to align the design with
> > > > applications' expectations.
> > > Is that the cygwin terminfo or the xterm terminfo you're talking about?
> > > 
> > > In case of the cygwin terminfo, that would mean the cygwin terminal
> > > emulation behaves differently from the terminfo for ages.  I guess
> > > you're right then, we should fix this in the cygwin terminal emulation
> > > to make sure it behaves as descibed in its terminfo.
> > > 
> > > In case of the xterm terminfo, that would be no problem because my patch
> > > drops the cursor movement for NUL.
> > Yeah, never mind, I checked the cygwin terminfo entry myself.
> > 
> > I pushed a patch removing the cursor movement on NUL and added
> > a matching comment instead.
> Great, thanks! And sorry I'm sometimes a bit slow to respond...

No worries, same here.  Thanks for the terminfo hint.
I created a new developer snapshot for testing.


Corinna

-- 
Corinna Vinschen
Cygwin Maintainer
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